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121408, Construction is underway along Corridor Q, a 14-mile section of highway in Southwest Virginia that will open to traffic in stages from 2023 to 2027. Preliminary data indicated that a newly established reintroduced herd of elk regularly travels on and alongside the partially constructed road. The purpose of this study was to determine potential design, placement, costs, and funding opportunities for wildlife crossing structures on Corridor Q should the decision be made to pursue this option to reduce the potential risk for elk-vehicle collisions. A criteria-based method was applied to 0.5-mile road segments to determine suitable locations for a series of crossing structures. Evaluated criteria included elk location data, surrounding land use, landscape features that encourage elk movement, roadside topography for cost-effective structure placement, and structure spacing decisions. Elk location data were obtained from 12 collared female elk in the “Corridor Q herd” (hereinafter “Corridor Q elk”). These locations were evaluated to determine elk use of the road segments, home range sizes and locations relative to the road, and habitat selection probability. Findings indicated that the use of the landscape by the elk herd has been shaped by the construction of Corridor Q. Approximately 38% of the 26,659 locations of the collared elk were within 200 meters of the nearly completed road sections, which provide elk an efficient means of travel to preferred habitat that is abundant along the roadside. Home ranges of all 12 collared elk overlapped with portions of Corridor Q road segments. Home ranges were shaped similarly to the partially constructed sections of Corridor Q, indicating the elk’s heavy use of the road to access preferred areas of habitat on both sides of the corridor. Distance to barren land, herbaceous cover, and shrub cover had the largest influence on elk habitat selection, all of which are a product of road construction and are distributed linearly along th

119821, Several state departments of transportation have recognized the benefits of modified asphalt mixtures in resisting multiple modes of climate-and load-induced distresses in flexible pavements. Throughout the past 50 years, asphalt binders have been modified with various components such as styrene-butadiene-styrene (SBS) polymers, ground tire rubber, chemicals (e.g., acid), recycled engine oils, etc., to achieve the desired properties. Hybrid rubber modified asphalt (HRMA) is an innovative engineered additive derived from ground tire rubber, elastomeric SBS polymers, and additive technologies. HRMA is specifically formulated to improve the high temperature stiffness and elastic properties of performance graded binders and the storage stability of modified binders. The purpose of this study was to document and assess HRMA field trials constructed in Virginia. This study documented and evaluated the constructability and laboratory performance of two plant-produced HRMA mixtures compared with the Virginia Department of Transportation (VDOT) typical SBS-modified surface mixtures as reference mixtures. No changes from routine established practices in terms of surface preparation, production at the plant, or paving operations were reported. The four mixtures were evaluated in terms of durability, dynamic modulus, resistance to rutting, and resistance to cracking using multi-level performance tests (basic, intermediate, advanced). All the derived observations indicated that HRMA modification could be as beneficial as regular SBS modification and could provide similar or better performance properties and characteristics for the resultant mixtures. The study recommends that VDOT consider the use of HRMA surface mixtures as an alternative to the current use of regular SBS-modified surface mixtures on higher-volume facilities. Since the sections evaluated in this study were placed in 2021, the 2-year performance data and corresponding observations are still considered preliminar

119789, Safety Service Patrols (SSPs) provide motorists with assistance free of charge on most freeways and some key primary roads in Virginia. This research project is focused on developing a tool to help the Virginia Department of Transportation (VDOT) optimize SSP routes and schedules (hereafter called SSP-OPT). The computational tool, SSP-OPT, takes readily available data (e.g., corridor and segment lengths, turnaround points, average annual daily traffic) and outputs potential SSP configurations that meet the desired criteria and produce the best possible performance metrics for a given corridor. At a high level, the main components of the developed tool include capabilities to: a) generate alternative feasible SSP beat configurations for a corridor; b)predict incidents and SSP characteristics (e.g., incident frequency, SSP service time) for a given SSP beat configuration; c) estimate performance measures (e.g., SSP response time, number of incidents responded to); and d) identify and present the best SSP configuration(s) through visual aids that facilitate decision making. To generate the incident data needed for the simulation-based SSP-OPT tool, a hierarchical negative binomial model and a hierarchical Weibull model are developed for incident frequencies and incident durations, respectively, based on the historical incident data. These models have been found to be effective in simulating the spatiotemporal distribution of incidents along highway corridors and for generating their attribute data (e.g., incident type, duration). The simulation program employs a discrete event-based approach and requires a few calibration parameters (e.g., SSP vehicle speed). After calibrating the model, the validation results show good agreement with field observations when applied to a sample SSP corridor from I-95. A user interface is created for the SSP-OPT tool in MS Excel to facilitate data entry and visualization of the output metrics for a given corridor. The output includes th

119790, Transit ridership data comprise one of the performance metrics examined when allocating funding to transportation projects, especially for those designed to reduce traffic congestion. The better the quality of the data, the more efficient the project prioritization process. The purpose of this study was to obtain better ridership data by answering three questions using Virginia-based data: How is transit ridership affected by changes to infrastructure and transit service such as the addition of real-time information systems, shelters, and lighting or increases in service frequency? What percentage of transit ridership occurs during peak hours of congestion? How does crowdsourced transit activity data compare to ridership data from Virginia transit agencies? Study methods included conducting extensive literature reviews to determine previous findings related to ridership effects of stop improvements and then conducting a before-after study in Virginia using ridership data from one Virginia transit agency.

The effect of 8-in. wide edgelines on the incidence of run-off-the road (ROR) and related accidents was evaluated. The treatment locations consisted of three two-lane rural road sections totaling 55.2 miles. A before-and-after design with a comparison group, and a check for comparability were used to analyze data. Five years of accident data, covering the three years before wide edgeline installation and the two years after installation, were used. It was concluded that there is no evidence to indicate that wide edgelines significantly affected the incidence of ROR and related accidents for any individual treatment location or for the locations combined. The related accidents include ROR accidents involving driving under the influence of alcohol or drugs, ROR accidents on curves, ROR accidents during darkness, and opposite-direction accidents. Consequently, it was recommended that wide edgelines not be considered as a countermeasure for ROR accidents in Virginia.

The study examined the condemnation process in the Virginia Department of Transportation (VDOT) by collecting information from attorneys, appraisers, judges, VDOT managers and staff, and other condemnors both within and outside Virginia. Of particular interest were alternatives that exist to the present procedure for selecting the condemnation tribunal and a determination of whether such alternatives hold promise for overcoming difficulties that may be associated with the existing system. A number of initiatives are identified that, if implemented, may result in improvements in Virginia's condemnation process. They include increasing the use of contract appraisers, especially in highly controversial cases; additional training for staff appraisers and negotiators; review of past cases in which awards were excessive; greater use of pretrial discovery; and, consideration of an alternative to the current methods for composing and selecting condemnation tribunal.

Chloride-induced corrosion causes significant deterioration in transportation structures where uncoated reinforcing steel is used. Concretes having a very low permeability are used to prevent the intrusion of chlorides into concrete to the level of the reinforcing steel. This study evaluates the strength and permeability of various combinations of silica fume and slag in concrete. It was determined that when silica fume is added in small amounts (3 to 5 percent) to concretes that have up to 47 percent slag at a water-cement ratio of 0.40 and 0.45, economical concretes with very low permeability and adequate strengths can be produced.

116425, The objective of this study was to evaluate the influence of production variability on performance test results to determine if mixtures balanced during design could become unbalanced during production. Fourteen currently accepted mixture designs, 10 BMD mixtures and 4 Superpave mixtures (to serve as a comparison between current standards and BMD designs), were recreated in the laboratory. Additionally, the mixes were adjusted to produce coarse and fine gradations and high and low binder contents according to currently accepted tolerance limits to simulate production variability. Two interaction mixtures assessing changes in gradation and binder content were evaluated as well as two critically aged mixtures.

Because intellectual property is a dynamic field of law, this handbook is neither a, comprehensive guide nor an accurate predictor of legal developments. This handbook, is merely an effort by the Virginia Transportation Research Council to provide VDOT, employees guidance in addressing the intellectual property issues they may face during, the scope of their employment. This handbook is not a substitute for professional legal, advice. If you need more detail concerning your individual rights and duties, you should, consult an attorney., This handbook will be reviewed annually and revised periodically as warranted, by changes in the law and governmental policy. This updated handbook is intended to, replace the March 2002 edition. The organization of the handbook was modified to, focus on intellectual property issues related to VDOT.

The transport of hazardous and dangerous materials (HAZMAT) through safety-critical facilities poses significant risk to overall system reliability should those assets be incapacitated by the occurrence of a related incident. This problem is particularly acute for facilities in remote locations such as Virginia’s mountain tunnels on Interstate 77 (I-77) due to limitations on alternate routes and the availability and proximity of emergency responders and specialized equipment/supplies. Automated placard reader systems (APRSs) are commercially available camera-based computer vision systems that “read” hazardous material placards on passing trucks from roadside installations. This information, along with other pertinent vehicle identification data may then be forwarded to critical facility operators to inform any preparations or responses that may be required. The Virginia Tech Transportation Institute conducted an initial phase of work to assess the readiness of APRSs for their reliable and effective roadside deployment and to determine how the data from such a system could be used by facility operators to improve safety and mitigate disruption during an event involving HAZMAT. The findings of the first phase of work indicated that available APRS technology was sufficiently advanced to warrant a second phase of work that included field testing and further refinement of the preliminary deployment plan. In Phase I, an APRS from Intelligent Imaging Systems (IIS) was identified for further evaluation. In this (second) phase of work, a mobile APRS system provided by IIS was evaluated under experimental and naturalistic scenarios at the Virginia Smart Roads and at several locations on Virginia public roads. A photographic survey of public HAZMAT placard usage conducted previously was used to inform this testing. Additional naturalistic data were acquired from a permanent APRS installation in Delaware when difficulties with the mobile APRS were encountered. The mobile and pe

119857, The Virginia Department of Transportation (VDOT) has been working toward the implementation of balanced mix design (BMD) for several years. During that time, special provisions have been developed to address dense-graded surface mixtures with reclaimed asphalt pavement (RAP) contents up to 30% and with RAP contents of 40% and above. In 2020, five field trials encompassing 12 mixtures were constructed to evaluate BMD mixtures designed and produced in accordance with VDOT’s special provision for surface mixtures with high RAP contents. Typical dense-graded Superpave surface mixtures were used as controls. This study documented and assessed these trials to provide information to evaluate the impact of various RAP contents and additives, production variability, reheating, and binder properties on BMD performance test results. Twelve mixtures were evaluated during the five field trials. The mixtures included combinations of different RAP contents, two binder grades, four recycling agents, and fiber. Volumetric and gradation analysis was performed on the mixtures. The Cantabro mass loss test (Cantabro test), the indirect tensile cracking test (IDT-CT), and the Asphalt Pavement Analyzer (APA) test were performed on laboratory-produced design specimens and non-reheated and reheated plant-produced, laboratory-compacted specimens. All findings and conclusions are limited to the mixtures evaluated. Based on the test results, mixtures containing 35% or greater RAP contents, softer binders, recycling agents, and fiber may be designed and produced to meet current BMD performance thresholds and current volumetric properties, gradation, and asphalt content requirements. It was found that some mixtures that were volumetrically designed under current VDOT specifications met BMD requirements. In addition, the expected trends in mixture performance testing were not always observed, likely due to masking by variability due to specimen fabrication practices or by inherent test variabilit

The most recently published update of the Virginia Department of Transportation’s (VDOT’s) historic bridge management plan, A Management Plan for Historic Bridges in Virginia: The 2017 Update, noted a number of special considerations regarding stone masonry on VDOT’s historic bridges (i.e., those state-owned bridges that are individually eligible for or listed on the National Register of Historic Places). Key considerations included the types of masonry work identified on management plan bridges; various types of repair and stabilization methods; and references to compatible mortars for use on bridges of older construction. The 2017 update of the historic bridge management plan also contained a fifth recommendation: conduct an in-depth historic masonry study and produce a best practices document identifying procedures for repair and/or rehabilitation of historic masonry structures and masonry components, particularly those on VDOT’s historic bridges. This study addressed that fifth recommendation. This study assembled data related to masonry in historic bridges, including archival documentary evidence, materials, and construction and repair technologies, and yielded a best practices document for facilitating appropriate management of VDOT’s historic bridges with stone masonry components. The study concluded that (1) historic bridges in Virginia with stone masonry construction exhibit a number of different forms, materials, building practices, and technologies that reflect the time periods when the bridges were built; (2) a variety of maintenance, repair, and rehabilitation practices have been used on these bridges; (3) best practices in historic preservation can evolve over time as additional information is acquired; and (4) knowledge of these various forms, materials, practices, and technologies, and the necessary specialized treatments required, must be taken into account when planning and undertaking maintenance, repair, and rehabilitation for the various types o

119593, Chapter 19 of the Highway Safety Manual (HSM) provides safety performance functions (SPFs) for freeway ramps and crossroad terminals. The chapter includes 56 predictive models for ramp terminals characterized by terminal type, intersection control, crash severity, area type, and number of crossroad lanes. These SPFs were developed with data from other states and need to be calibrated to Virginia conditions to ensure that they accurately reflect the driver population and environment. The application of uncalibrated SPFs may produce misleading results, compromise safety outcomes, and lead to inappropriate design decisions. This study conducted systematic calibration of the HSM ramp terminal SPFs to account for conditions in Virginia. This involved determining appropriate multipliers or functions that aligned the expected average crash frequencies estimated using HSM methodologies with field-observed crash frequencies from selected sites. A review of cumulative residual plots for fitted values suggested that using a single calibration factor as a multiplier to adjust the HSM ramp terminal SPF predictions did not provide a good fit to Virginia data. Consequently, calibration functions were developed that provided a better fit of Virginia data to the HSM ramp terminal SPF predictions. Limiting the number of crash modification factors to 3 instead of using all 11 applicable crash modification factors resulted in a marginally better fit of the data.

119819, Many state highway agencies are currently exploring a new approach for designing and accepting asphalt mixtures, known as the balanced mix design (BMD) method (hereinafter “BMD”). The Virginia Department of Transportation (VDOT) has made a commitment to adopt BMD to enhance the performance of asphalt mixtures. Since 2018, VDOT has taken incremental steps to phase in the use of BMD in production while addressing concerns expressed by VDOT and the industry. The use of BMD line items in selected 2021 and 2022 contracts has been an important learning opportunity for VDOT and the industry along the path to implementation. This study documented and assessed the 2021 and 2022 maintenance plant mix schedule pilots. The objectives of the study were to provide information on quality control, acceptance testing, and independent assurance testing; analyze the performance properties of reheated mixtures and extracted and recovered binders; and document lessons learned from the process. The analysis addressed several topics, including variability in production and testing and binder characterization and implications for performance. The pilot projects were developed by the VDOT districts using maintenance plant mix schedule contracts. In 2021, approximately 72,000 tons of BMD mixtures were paved on selected routes in 10 maintenance schedules across five districts. In 2022, approximately 222,000 tons of BMD mixtures were paved in 13 maintenance schedules distributed across all nine VDOT districts, with at least one BMD contract executed per district. The Cantabro mass loss test, the indirect tensile cracking test (IDT-CT), the Asphalt Pavement Analyzer rut test, and the indirect tensile test at high temperature (IDT-HT) were performed on laboratory-produced design specimens and non-reheated and reheated plant-produced, laboratory-compacted specimens. Basic and advanced binder testing and analysis were conducted on extracted and recovered binders from selected samples of the mixtur

119604, This study assessed the short-term functional (surface) characteristics of pavements constructed using dense-graded asphalt surface mixtures designed with the balanced mix design (BMD) methodology as compared to counterpart mixtures designed using the existing design methodology (Superpave). Another objective of this study was to establish a functional performance baseline for the Virginia Department of Transportation’s (VDOT) BMD trial mixtures constructed in the 2019 through 2021 construction seasons in terms of friction and macrotexture. This study also sought to define a potential empirical relationship to link mixture volumetric properties to the surface characteristics of asphalt mixtures in terms of macrotexture. In this effort, 52 different field projects encompassing pairs of BMD and control mixtures with service lives ranging from 0.1 to 2.8 years were surveyed for friction, macrotexture, and pavement roughness. Descriptive statistics and parametric statistical techniques were used to identify systematic trends or differences in the functional characteristics of the pavements.

120025, Accurate prediction of travel time reliability measures would help state departments of transportation set performance targets and communicate the progress toward meeting those targets as required by the Moving Ahead for Progress in the 21st Century Act (MAP-21). In a recent Virginia Transportation Research Council study, Methods to Analyze and Predict Interstate Travel Time Reliability, researchers developed and tested statistical and machine learning models to analyze and predict travel time reliability on interstate highways. The generalized random forest (GRF) model showed promise in terms of data processing (no need for pre-clustering of travel times) and the relative accuracy of the results and was recommended for further evaluation by the study’s technical review panel. The current study directly adapted the previously developed GRF models to meet the requirements of MAP-21 federal target setting. In particular, the GRF approach developed using the INRIX Traffic Message Channel network for weekday peak period traffic by the prior study was successfully (1) adapted to the federally required National Performance Management Research Dataset (NPMRDS) network, and (2) expanded to cover the weekday midday and weekend daytime periods. The technical review panel was also interested in practical steps to implement the predictive models. To that end, suggested procedures for applying the new GRF models—including relevant model inputs and data preparation steps—are documented in this report. Direct application of the GRF models trained with INRIX data (2017-2018) to predict travel time reliability measures in 2009 on the NPMRDS network highlighted the need for developing new GRF models targeted to the NPMRDS network, especially when the 90th percentile travel time was predicted. Whereas the INRIX models showed mean absolute percentage errors of 37% and 51% for freeway and interchange segments, respectively, for the PM peak hours, the new GRF models (trained with 2017-20

69A3551747115/Project 05-113, Automated shuttles are small, low-speed (generally less than 25 mph) vehicles that do not require a human operator, though to date all have included an onboard human attendant. This project aims to assess the limitations that the EasyMile EZ10 Gen 3 low-speed automated vehicle (LSAV) encountered while operating on public roadways. The primary interests are to evaluate the infrastructure elements that posed the most challenges for the LSAV during its deployment. Further, the EasyMile EZ10 Gen 3 is advertised as being capable of operating at SAE International Level 4 Automated Driving System capability in certain ODDs. Accordingly, the team deployed the LSAV with the expectation that it would be operated at SAE Level 2 capability. The human safety operator was required to intervene in scenarios beyond the vehicle’s automated functional capability. The results of this analysis indicated that the LSAV operated at a lower than expected speed, experienced a high frequency of disengagements, and had a regular need for safety operator intervention. These results suggest that the EZ10 Gen 3 vehicle is not yet operating at SAE International Level 4 capability on routes with moderate complexity.

118543, The loss of vegetation from roadside activities can lead to erosion and an increased sediment load in stormwater ponds. Current VDOT procedures regarding approved seed blends and establishment practices have led to inconsistent vegetation establishment and greatly rely on introduced species. Growing concerns regarding the threat of introduced, invasive species have increased the promotion of native plants in landscapes. One example is VDOT’s participation in the Candidate Conservation Agreement for monarchs fostering a desire to better understand factors that may improve milkweed abundance. Native seed blends, however, have failed to produce soil stabilization or long-term establishment in the past, presumably because of erroneous species selection, seed dormancy, and competitive displacement by weedy vegetation. This study was conducted to (1) identify and document potential procedural improvements for successful roadside vegetation establishment in Virginia; (2) propose candidate native plants for VDOT see blend consideration based on a statewide plant community assessment on Virginia roadsides; and (3) summarize the literature on availability, cost, and establishment success of candidate native species. A review of VDOT’s vegetation establishment practices indicates that procedural inconsistencies related to the development of Roadside Development Sheets and recent restrictions on fertilizer application may be contributing to vegetation establishment failures. A statewide plant community assessment evaluated 490 sites and identified 616 unique plant species among the 67,330 plants surveyed. The Shannon Diversity Index was calculated for 2,450 10-m transects, indicating that plant biodiversity was higher on low-maintenance distal backslopes compared with high-maintenance road edges, shoulders, and ditches. Plant biodiversity was also higher on secondary roads than on primary roads. The unique introduced species encountered were relatively stable across Virginia’s

117955, High-density polyethylene (HDPE) is widely used for above-ground storage tanks (ASTs). However, there are currently no guidelines for non-destructive testing (NDT) and evaluation (NDE) of HDPE ASTs. Moreover, the feasibility, limitation, and challenges of using non-destructive testing techniques for field inspection of HDPE ASTs have not been studied yet. This study explored the viability of HDPE AST inspection using infrared thermography (IRT) and ultrasonic testing (UT). The results indicate that: 1) ambient environmental parameters can affect IRT accuracy; 2) there is an ideal time during the day to perform IRT; 3) the heating source and infrared camera orientation can affect IRT accuracy; and 4) with proper measures taken, IRT is a promising method for flaw detection in HDPE ASTs. Additionally, UT can be used following IRT for detailed investigation to quantify the defect size and depth. The manuscript concludes with a discussion of limitations and best practices for implementing IRT and UT for HDPE AST inspection in the field.

118055, Transportation planning practices increasingly require knowing the number of occupants per vehicle. Except for manual observations, Virginia has two data sources for obtaining occupancy: the American Community Survey and the National Household Travel Survey, neither of which provides corridor-specific values. This study developed an approach for estimating occupancy based on crash records data—now feasible because Virginia routinely collects, for each crash, the total number of occupants regardless of injury status. This occupancy is not widely available because of privacy concerns but can be obtained through a special tabulation performed by VDOT’s Traffic Engineering Division. Having crash data is not a panacea: as the area of interest shrinks from a district to a roadway segment, the likelihood that crashes alone provide a biased estimate of occupancy increases. Accordingly, the recommended approach for detecting occupancy contains two additional steps beyond extracting crash data: (1) at the jurisdiction level, test whether this bias exists by performing an eta-squared test; if appropriate, perform Type 1 bias correction by ensuring all occupancy groups (e.g., three occupants per vehicle) are synthesized in the crash data set; and (2) at the corridor level, perform Type 2 bias correction by building a correction model incorporating field observations. Yet bias is not necessarily a fatal flaw. At the corridor level, the mean average absolute difference between occupancy based on uncorrected crash data and occupancy collected from field observations was 0.06; use of the Type 2 bias correction model showed a difference of 0.05 between field observations and corrected data when the model was used on a set of data not used to build the model. At the jurisdiction level, the difference between uncorrected occupancies and Type 1 bias correction was never above 0.02 as long as at least 200 vehicles are observed in crashes. This method allows Virginia to estimate occupanc

114311, Poor subgrade often requires in-place stabilization or removal by excavation and replacement with suitable material. Chemical stabilization with cement or lime is a common remediation practice. This study investigated the use of No. 10 screenings, a quarry byproduct finer than the 4.75-mm (No. 4) sieve, as a means to improve poor subgrade conditions. Three sources of screenings with two marginal soil types at various mixture rates were studied in the laboratory to determine an appropriate field application. The engineering improvements were determined using the California bearing ratio, density, plasticity reduction, and resilient modulus. At a mix rate of 50% by weight, increased density, reduced optimum moisture content, and reduced plasticity were observed. Some improvements for the clayey soil as measured by the soaked California bearing ratio were observed, but none for silty soil. Improvement in the resilient modulus, which is the subgrade support value for mechanistic pavement design, was not obvious and depended on the field moisture condition. No improvement in resilient modulus was observed at the field equilibrium moisture condition predicted by the Mechanistic-Empirical Pavement Design Guide using the Thornthwaite moisture index model, as amended subgrade seems to achieve equilibrium at or near 90% degrees of saturation.

69A3551747115/Project: 06-008, As new Intelligent Transportation Systems (ITS) and vehicle-to-everything (V2X) communication technology and protocols continue to emerge, additional training is needed for personnel working in the transportation sector. The Virginia Department of Transportation has already created a training program focusing on general topics pertaining to connected and automated vehicles (CAVs) and has recently identified a need for a more specific program focusing on communication technologies. To address this need, the Virginia Tech Transportation Institute team developed a 60-minute online learning program that includes a series of 10 narrated modules with slides, images, charts, videos, and learning assessments. The training provides a high-level overview of the types of communications that support ITS, traffic management, and connected vehicle environments. The training includes descriptions of the communication technologies, protocols, performance metrics, use cases, and data security. The included communication technologies are currently being utilized by infrastructure owner-operators (IOOs), original equipment manufacturers (OEMs), and industry technology providers.

The adequate spacing and design of access to crossroads in the vicinity of freeway ramps are critical to the safety and traffic operations of both the freeway and the crossroad. The research presented in this report develops a methodology to evaluate the safety impact of different access road spacing standards. The results clearly demonstrate the shortcomings of the AASHTO standards and the benefits of enhancing them. The models developed as part of this research were used to compute the crash rate associated with alternative section spacing. The study demonstrates that the models satisfied the statistical requirements and provide reasonable crash estimates. The results demonstrate an eight-fold decrease in the crash rate when the access road spacing increases from 0 to 300 m. An increase in the minimum spacing from 90 m (300 ft) to 180 m (600 ft) results in a 50 percent reduction in the crash rate. The models were used to develop lookup tables that quantify the impact of access road spacing on the expected number of crashes per unit distance. The tables demonstrate a decrease in the crash rate as the access road spacing increases. An attempt was made to quantify the safety cost of alternative access road spacing using a weighted average crash cost. The weighted average crash cost was computed considering that 0.6, 34.8, and 64.6 percent of the crashes were fatal, injury, and property damage crashes, respectively. These proportions were generated from the field observed data. The cost of each of these crashes was provided by VDOT as $3,760,000, $48,200, and $6,500 for fatal, injury, and property damage crashes, respectively. This provided an average weighted crash cost of $43,533. This average cost was multiplied by the number of crashes per mile to compute the cost associated with different access spacing scenarios. These costs can assist policy makers in quantifying the trade-offs of different access management regulations.

SMA is a gap-graded mix filled with a rich asphalt-fines mastic developed in Europe. In 1991 five states constructed trial sections to determine if satisfactory mixes could be produced in the United States with current materials and high rates of production. This report discusses Virginia's first section, placed in 1992 near Lynchburg. During construction, better equipment was necessary to control the amount of fines contained in SMA mixes. Lack of control in the mix gradation caused variability on the roadway and on routine mix tests conducted during construction. The mix containing the cellulose fiber, Arbocel, has rotted more at stop-lights than the mix containing the polymer, Vestoplast, or the high-stability control mix. However, all mixes continue to perform well. Laboratory creep tests and gyratory shear tests predicted that the control mix and Vestoplast mix would be more resistant to rutting and consolidation under traffic. This investigation and work in other states have improved the current Virginia specification for SMA. The gradation was coarsened, a stiffer asphalt cement was required, and plant equipment that can adequately handle the aggregates was used. With these changes, future installations will perform better than the current dense graded mixes.

In early 2013, construction began on a Virginia Department of Transportation (VDOT) project to install an Active Traffic Management (ATM) system on I-66 from US 29 in Centreville to the Capital Beltway (I-495). Construction was completed in September 2015. This project was intended to improve safety and operations on I-66 without physically expanding the roadway through better management of the existing facility. The main components of the installed system included advisory variable speed limits (AVSL), lane use control signals (LUCS), and hard shoulder running (HSR).

118420, Public engagement is an important and required element of the transportation planning process. Since the onset of the COVID-19 pandemic, public engagement has shifted dramatically. Agencies of all sizes accelerated their transition to virtual engagement in 2020 to comply with shelter-in-place orders and social distancing guidelines. Social media and online engagement tools have become integral components of engaging the public and have effectively removed the time constraints of in-person meetings, offered opportunities for community members to engage in new and interactive ways, and brought new voices into the engagement process. In early 2020, when the pandemic effectively ceased in-person meetings, the Virginia Department of Transportation (VDOT) expanded its use of virtual platforms to engage with the public and is continually seeking to improve public involvement during the transportation planning and project development process, as traditional meetings are often not well attended, feedback is sparse, and participation can be limited to special interest groups. The purpose of this study was to assess the role of virtual public engagement in VDOT’s business practices, examine its potential to reach a broader public, and document lessons learned for improved efficacy. The scope of the study was focused primarily on transportation planning public information meetings where on-demand public input has been frequently used as a substitute for in-person meetings, especially during the height of the pandemic. Based on the study findings, the study concluded the following: the benefits of virtual public engagement in terms of increased participation are widely acknowledged; virtual public engagement challenges exist, particularly with respect to achieving participation from underserved communities; outreach avenues exist to improve participation levels of underserved communities; and a hybrid approach of in-person and virtual events is likely to be the future of public

The Virginia Transit Performance Evaluation Package (VATPEP), a computer software package, is documented. This is the computerized version of the methodology used by the Virginia Department of Transportation to evaluate the performance of public transportation systems supported by public funds in the Commonwealth of Virginia. The technical steps in the process are entering, printing, and editing data; validating data; evaluating performance; and printing annual report data and graphs. A Pascal program supplemented by graphics from Lotus 1-2-3 comprises the package.

This series of observational surveys, to determine child safety seat use in Virginia, began in 1993 at the request of DMV officials. During all 4 years (there was no survey in 1995), data in metropolitan areas were collected at the same locations, at the same time of day and day of week, and according to the same criteria for determining use. In 1997, data collection was added for safety restraint use by occupants 4 to 16 years of age at the request of officials of the Department of Health, which is now responsible for the state's child safety seat program. In addition, data were collected on whether any booster seats in use were being used properly. Seven sites were also added in communities with a population between 50,000 and 100,000 (mid-size cities). For the entire vehicle, the 1997 metropolitan area child safety seat correct use rate was 54.1 %, incorrect use was 17.4%, and non-use was 28.5%. Non-use was greater in the front seats (42.1 %) than in the rear seats (25.2%). The western area had the highest non-use rate (50.0%) and the lowest correct use rate (32.1 %). Non-use and correct use in Northern Virginia, Central Virginia, and Tidewater were similar, with correct use ranging from 53.1% to 58.7% and non-use ranging from 24.8% to 29.1 %. Child safety seat use in the three areas categorized as mid-size cities (Charlottesville, Danville, and Lynchburg) was lower than in the metropolitan areas: correct use was 43.2%, incorrect use was 14.8%, and non-use was 42.0%, with Danville having the highest non-use rate at 61.9%. Non-use was higher in the front seats (66.7%) than in the rear seats (37.7%). Safety restraint/seat belt use by occupants 4 to 16 years old riding in the rear seats was very low. In the metropolitan areas, correct use was 34.9%, incorrect use was 2.3%, and non-use was 62.9%, with the western area having the highest non-use rate (69.3%). In the mid-size cities, correct use was 26.2%, incorrect use was 1.5%, and non-use was 72.3%, rates considerab

102892, Roller-compacted concrete (RCC) is a stiff mixture of aggregate, cementitious materials, and water with zero slump. RCC, is consolidated or compacted in the fresh state by use of a roller with or without vibration. RCC typically is placed with asphalt, paving equipment in thicknesses of 4 to 8 in for pavement application. RCC has gained the attention of the paving industry in, recent years because of its history of low cost, rapid construction, and durable performance. The Virginia Transportation, Research Council conducted this laboratory study to gain familiarity with RCC technology and to develop guidelines for its use, in the field., RCC mixtures were successfully produced in the laboratory using locally available materials, and their properties were, measured. These mixtures achieved compressive strengths around 5,000 psi in 28 days and had properties similar to those of, conventional concrete in terms of compressive strength, modulus of elasticity, modulus of rupture, and splitting tensile strength., A special provision was developed and used in the two field projects. The special provision was subsequently modified based on, the field experience and is provided in the Appendix., VDOT should implement the RCC specification developed in this study for regular VDOT use of RCC. Use of RCC, should be considered in future field applications, particularly where fast construction of rigid (concrete) pavement is needed; an, example of such an area would carry heavily loaded, slow-moving vehicles such as at intersections and access roads to truck or, bus parking areas. VDOT should annually monitor the long-term performance of the two constructed RCC projects reviewed in, this study over a period of at least 10 years. Evaluations should document joint efficiencies for load transfer (through testing with, the falling weight deflectometer), any visual evidence of deterioration of asphalt at joints, and any other general signs of, pavement distress that may occur.

104117, When new agritourism land uses are initially proposed, a lack of data on how many vehicle trips these uses tend to create, (known as trip generation) means that there is limited guidance available for transportation planners and engineers to make, appropriate and sound recommendations regarding entrances and other traffic improvements. Agritourism land uses can include, farm wineries, breweries, distilleries, orchards allowing visitors to pick fruits and vegetables, and farm stands and markets. This, study reviewed existing information about agritourism trip generation rates and conducted data collection and analysis with regard, to these rates at five winery and cidery sites in Virginia. In Virginia, localities have the ability, albeit limited, to regulate special, events held at agritourism sites, so this study looked at non-event trip volumes., Engineers and transportation planners typically use trip generation data from the Institute of Transportation Engineers’ Trip, Generation Manual to determine entrance categories and to recommend street improvements and strategies for safety or capacity., The manual includes trip rates for several uses that could be considered related but that do not exactly represent the range or, character of agritourism uses, with the possible exception of breweries serving a full menu approximating the manual’s definition, of “quality restaurant.” The data reported in the manual for most of these agritourism-related uses had a large degree of, variability. Recent studies of trip generation at wineries, all from California, were also reviewed., Data collected for the five Virginia sites had high variability, but certain independent variables had moderately high, correlations with trips: (1) number of employees, (2) population within a 60-minute drive, (3) households within a 60-minute, drive, and (4) square footage of tasting room. Although based on a small sample size, the results suggest that established retail, wineries/cideries are likely to exceed the Virginia Department of Transportation’s 50-trips-per-day maximum threshold for a “low, volume commercial entrance,” falling instead into the “moderate volume commercial entrance” or the “commercial entrance”, category., Based on the findings of this study, it appears that VDOT’s practice of assuming low trip volumes for agritourism land uses, may result in entrances that are undersized for the amount of traffic they carry. The “moderate volume commercial entrance”, category may be appropriate for agritourism land uses in most cases. In addition, weekday peak hour volumes for the agritourism, land use sites studied did not occur during the weekday peak hours of adjacent streets. Promising site-based variables for Virginia, wineries include square footage of a tasting room and number of employees at peak season, and when no site-based variables are, available other than location, Census-derived variables can provide some information. Additional research could clarify the, findings of this study., Recommendations for VDOT’s Office of Land Use include (1) providing guidance to VDOT’s transportation and land use, directors indicating that retail-focused wineries can be assumed to generate well more than 50 vehicle trips per day at peak season, and (2) investigating possible adjustments to the traffic volume thresholds for the “moderate volume commercial entrance”, category.

The Tom's Creek Bridge is a small-scale demonstration project involving the use of fiber-reinforced polymer (FRP) composite girders as the main load carrying members. It is a simply supported, short-span bridge located along Tom's Creek Road in Blacksburg, Virginia. As a result of discussions among Virginia Tech, Strongwell, the Virginia Department of Transportation, and the Town of Blacksburg, the existing deteriorated superstructure of the Tom's Creek Bridge was replaced with a glue-laminated timber deck on 8 in (20.3 cm) deep pultruded fiber-reinforced polymer beams. The project was intended to address two issues. First, by calculating bridge design parameters such as the dynamic load allowance, transverse wheel load distribution and deflections under service loading, the Tom's Creek Bridge will aid in modifying current AASHTO bridge design standards for use with FRP composite materials. Second, by evaluating the FRP girders after being exposed to controlled laboratory and service conditions, the project will begin to answer questions about the long-term performance of these advanced composite material beams when used in bridge design. A dynamic load allowance, IM, of 0.90 is recommended for the Tom's Creek Bridge. This value is the largest average IM observed and is therefore conservative. This value is significantly higher than those set forth in the AASHTO standards of 0.33 (AASHTO, 1998) and 0.30 (AASHTO, 1996). It is recommended to use a value of L/425 (LRFD Specification) or L/500 (Standard Specification). This value is consistent with AASHTO deflection control criteria for an all timber bridge. It is recommended to use the AASHTO wheel load distribution factors for a glulam timber deck on steel stringer bridge. There is no indication of loss of FRP girder ultimate strength after 15 months of service. Given the low service loads (no more than 10% of the ultimate capacity) and traffic volume the fatigue life prediction model suggests that fatigue will not be

In May 2002, Virginia's Commonwealth Transportation Commissioner tasked his Chief of Technology, Research & Innovation with leading an effort to develop a definitive, consistent, and well-documented approach for estimating the cost of delivering construction projects. A task force that included Virginia Department of Transportation (VDOT) central and district office staff, Virginia Transportation Research Council staff, Commonwealth Transportation Board members, and a metropolitan planning organization member was formed to either locate a well-founded, tested method for estimating project costs that could be adapted for use by VDOT or develop one. The task group found that a VDOT district had been using an estimation worksheet for several years that produced consistent and reliable results for certain types of roadway and bridge construction. The task group determined that no other method examined had the specificity and potential of this tool. The project team expanded the tool by collecting extensive project data and obtaining evaluations of VDOT project management personnel statewide to develop it further. The existing Excel worksheet with roadway and bridge estimates was expanded to include construction engineering, to be applicable for interstates, and to generate estimates for right-of-way and utilities costs. Data on completed projects were collected from all VDOT districts to help calibrate the model further to account for cost variations across the state. The task group also recognized early on that a very strong focus on project scoping was essential to accurate project estimation. A previous VDOT scoping committee had determined that VDOT did not have a consistent, uniform method that was being used statewide to scope projects. As a result, project cost estimates made at the scoping stage often did not hold up over time because key project features were invariably overlooked. The result was inaccurate estimates. Testing of the cost estimation tool was com

Laboratory creep and fatigue testing was performed on five Superpave surface hot-mix asphalt mixtures placed at the Virginia Smart Road. Differences in creep and fatigue response attributable to production and compaction methods were investigated. In addition, changes in creep response resulting from differences in specimen size were evaluated. Further, an evaluation of the effects of loading frequency, presence of rest periods, and specimen location within the pavement on fatigue life was conducted. Creep compliance values were determined using viscoelastic-based calculations, and time-temperature superposition was used to generate mastercurves. Reported creep compliance response models from the literature were found inadequate for accurately describing the creep compliance mastercurves generated during this study. Differences in creep response between specimens of different sizes were found to be due to specimen and test variability, rather than size. An evaluation of the effects of laboratory and plant production and laboratory and field compaction was inconclusive as material variability appeared greater than production or compaction variability. Simple regression models were found to be satisfactory for use in the development of prediction models for fatigue, although test data are necessary for calibration to particular mixture types. No relationships were found between fatigue model coefficients and volumetric properties of the mixtures tested because of the limited range of volumetric properties. Variability in volumetric properties between the mixtures produced at the plant and those produced to match the job mix formula did not significantly influence the predicted laboratory fatigue performance. Laboratory fatigue lives were similar between the laboratory-compacted fatigue specimens and specimens cut from the pavement; differences observed in performance were attributable to different air void contents. Predicted fatigue life was found to be statistically

A number of state departments of transportation, including the Virginia Department of Transportation (VDOT), are developing a geographic information system (GIS) to integrate data and to conduct more elaborate analyses which will improve their decision-making capabilities. Research is currently being conducted at the Virginia Transportation Research Council to determine some of the problems associated with the implementation of this relatively new and evolving technology. The collection and development of the data sets required to drive the GIS have been identified as two of the largest expenses associated with GIS implementation. This research looked at the feasibility of using the Global Positioning System (GPS) to collect some of the locational and attribute data required to run VDOT's GIS. Data sets identified in VDOT's 10-Year GIS Strategic Plan were collected and transferred to ARC/INFO ®, a proprietary system, by way of hand-held, mapping-grade GPS receivers. Methods for the collection and transfer of the data sets were outlined. Point accuracies of approximately 2 m were obtained. Time requirements and data collection problems were also described. These findings should ultimately aid VDOT in its GIS implementation process.

The Virginia Department of Transportation's (VDOT) Safety Service Patrollers (SSP) use different color uniforms depending on their geographic location. Red jumpsuits are used in the Northern Virginia District, orange jumpsuits are used in the Fredericksburg District and by the Tidewater Tunnel Patrollers, and white shirts and blue pants with a flagger's vest are used in the Suffok District. The purpose of this research was to identify and evaluate various colors and configurations of retroreflective materials for use on the SSP uniform in an effort to maximize employee safety. This study was to recommend a color, or colors; a pattern of retroreflective material; and the type of uniform that should be used as VDOT's standard SSP uniform. The scope of the project was limited to the use of existing materials and colors readily available from vendors. The uniforms selected for testing were evaluated under controlled conditions in the field. This evaluation consisted of photographing the existing SSP uniforms and the two prototypes on a closed portion of roadway with little to no external lighting. Photographs were taken of each uniform under daytime and nighttime conditions. A videotape was used to capture how the uniforms appear while a driver drives toward them during nighttime conditions under low and high beams. The videotape was also used to capture the ergonomic movements of the uniforms and how well the retroreflective tape depicted the actual movements as humans. In addition to photographing and videotaping the uniforms, the researcher made photometric measurements under daytime and nighttime conditions and laboratory colormetric measurements of each type uniform. The report concludes that fluorescent colors enhance the daytime conspicuity of highway worker's clothing. The literature indicates that fluorescent orange and fluorescent strong yellow-green are the two best colors for use on high-visibility clothing. Of the garments studied in the daytime portion of

Presented in this report is a detailed description of the procedure to be followed to develop a knowledge-based computerized expert system for determining whether to rehabilitate, improve, replace, abandon, or just to routinely maintain an old highway bridge in the VDOT road system. Based on extensive interviews with bridge engineering experts, the type of data needed, the rules to be used and interference procedures are described, along with an example for the expert system called DOB (for Disposition of Old Bridges). Future studies are expected to program this information into a format suitable for use in a personal computer.

The Virginia Transportation Research Council has been monitoring the use of child safety restraint systems in Virginia since 1983 through child safety seat surveys conducted annually (with the exception of 1995). The principal goal of the survey has been to estimate compliance with the relevant statutes in place at the time. Each year, data were collected from the four metropolitan areas of the state (northern, eastern, central, and western) at the same sites, on the same day of the week, and at the same hour of the day. In 1997, sites in three localities with a population between 50,000 and 100,000, referred to as mid-size cities, were added, as was data collection on safety belt use by occupants 4 to 16 years of age. This change was made because of changes to 46.2-1094 and 46.2-1095 of the Code of Virginia, which required these rear seat occupants to use safety restraints. In 1997, the percentage of children under age 4 seated in the front seat was in the double digits in every locality studied. Since then, the percentage of front seat passengers in this age group declined into single digits in all but one locality. Between 1993 and 1998, Metropolitan area survey results were characterized by a lack of consistent change, with correct use rates hovering in the 50s and mid-60s. In 1999, correct use rose to 83.2%. Similar trends had been seen in all four metropolitan areas, with the 1999 correct use rate ranging from 78.8% in the western area to 89.0% in the eastern area. A similar increase from 57.0% in 1998 to 84.6% in 1999 was noted in the mid-size cities. Lynchburg experienced the greatest increase, from 36.8% to 91.9%, with the rate in Charlottesville increasing to 88.5% and in Danville to 70.6%. In all three mid-size cities, incorrect use rates dropped to below 10%. In terms of restraint use among occupants 4 to 16 years of age, the picture is more complicated and not so positive. In the metropolitan areas, there was a modest increase in 1999 in correct restrai

This study was initiated with the goal of identifying the predominant factors affecting the achievable smoothness of asphalt overlays. In addition, the researcher chronicles the evolution of Virginia's innovative special provision for smoothness, which was developed specifically for maintenance-type resurfacing. The study also assessed the non-traditional equipment and methods used to comply with this smoothness special provision. Finally, the researcher provides a rational economic justification for the continued and expanded use of the pilot specification. Among the notable findings relating to achievable smoothness were the identified significant associations with functional classification, original surface roughness, and the use of the smoothness special provision. Factors that were found not to relate significantly to achieved smoothness include surface mix type, the use of additional structural layers, the use of milling, and time-of-day restrictions on construction activities (i.e., night paving). The dramatic increase in correlation between original and final surface ride quality when milling was used on the original surface was another interesting finding, as were the additional costs and corresponding additional benefits associated with the use of the specification.

Stainless steel-clad rebar provides an opportunity to significantly increase the Cl- threshold concentration associated with active corrosion initiation compared to plain carbon steel. However, threshold Cl- concentrations for 316L stainless steel-clad rebar are unknown. Moreover, the impact of possible galvanic corrosion between the clad layer and any exposed carbon steel core has not been investigated. The Cl- threshold concentrations for corrosion initiation on clad 316L stainless steel (with a thickness of about 1 mm over a carbon steel core), solid 316LN stainless steel, and plain carbon steel were examined in saturated Ca(OH)2 plus various concentrations of NaCl. The electrochemical properties of "intact" 316L stainless steel-clad rebar were found to be similar to those of solid 316LN stainless steel according to several electrochemical criteria. The Cl- threshold concentrations for corrosion initiation were increased to Cl-/OH- molar ratios as high as 17 to 24 even at high anodic potentials for "intact" 316L-clad and solid 316LN stainless steel, respectively. Thus, active corrosion of "intact" 316L-clad rebar could be delayed for many years due to the high Cl-/OH- molar ratios required at the stainless steel/concrete interface and the slow transport rate of chloride in concrete. In contrast, the threshold chloride concentration for corrosion initiation on carbon steel was low (Cl-/OH- molar ratio < 1.5) at all potentials. Cladding with a physical breech exhibited Cl-/OH- thresholds dominated by the exposed plain carbon steel. Galvanic coupling between exposed plain carbon steel and the stainless steel-cladding accelerated corrosion of the plain carbon steel only at and above the Cl-/OH- ratio necessary for corrosion initiation on carbon steel.

91023, This study developed traffic inputs for use with the Guide for the Mechanistic-Empirical Design of New & Rehabilitated Pavement Structures (MEPDG) in Virginia and sought to determine if the predicted distresses showed differences between site-specific and default traffic inputs for flexible and rigid pavements. The axle-load spectra, monthly adjustment factors, vehicle class distribution factors, and number of axles per truck inputs were considered. The predicted distresses based on site-specific traffic inputs from eight interstate and seven primary route weigh-in-motion sites in Virginia were compared to predicted distresses using MEPDG default traffic inputs. These comparisons were performed by use of a normalized difference statistic for each site-specific traffic input and the coefficient of variation for each pavement distress model. In addition, the practical significance for flexible pavements was considered from the difference in the predicted time to failure between site-specific and default traffic inputs. The analysis showed that the effect of the site-specific traffic inputs was generally not statistically significant when the uncertainty of the distress models was considered. However, the site-specific axle-load spectra and vehicle class distribution inputs showed a statistically significant effect on certain predicted distresses for flexible and rigid pavements, respectively. The study recommends that site-specific axle-load spectra data be considered for analysis of flexible pavements. Alternatively, summary (statewide average) axle-load spectra data for analysis of interstate and primary flexible pavements should be considered preferentially over default axle-load spectra. Site-specific vehicle class distribution factors should be considered for analysis of rigid pavements on the interstate system. Alternatively, summary (statewide average) vehicle class distribution factors for analysis of interstate rigid pavements should be considered preferentia

Problems with water penetrating into pavement were observed with the early coarse asphalt Superpave mixtures. There was justified concern that water would cause early deterioration; therefore, an effort was made to investigate the permeability problem and correct it. After an initial investigation revealed excessive permeability in many newly constructed Superpave pavements, the Virginia Department of Transportation's (VDOT) Materials Division decided that the potential permeability of mixtures should be determined during the mixture design phase prior to the start of construction. A technique of performing regressions of air voids and permeability with specimens prepared and tested in the laboratory was developed and refined at the Virginia Transportation Research Council. This investigation examined how well different labs agreed in two phases: one in which two VDOT laboratories participated and one in which contractors and VDOT laboratories participated. There was general agreement between laboratories in determining the acceptability of field samples of mixtures with regard to permeability. Potential difficulties and solutions in specimen preparation and regression analysis were discussed. The technique is currently being implemented by VDOT as a mixture design tool. It is estimated that the elimination of permeable mixtures that are not durable will save VDOT as much as $350,000 annually.

In the last decade, there has been increasing national concern about the adequacy of underwater inspection of bridge substructures. A number of factors have contributed to this concern, in particular the collapse of several major spans, some of which led to loss of life. Substructure failures have been the cause of bridge collapses and the subject of at least five National Transportation Safety Board (NTSB) highway bridge investigations. In at least four instances, deficiencies in the substructure could have been identified by underwater inspection. During this project, 425 bridges in Virginia were identified as requiring underwater inspection. It was concluded that assessments of the type and extent of damage to structures below the waterline prior to inspection are highly inaccurate. Prioritizing bridges for inspections must be based on an established history of underwater inspections. Trends in the deterioration of underwater structures indicate several factors to be considered in developing a priority system for an underwater inspection program. These trends are described, and time intervals for the inspection of bridges with a previous inspection history are suggested.

Notes on the attempt by the author to find documentation for the origin and validity of the designation of Route 29 in Virginia as the "Seminole Trail".

The Virginia Transportation Research Council has been collecting safety belt use data in Virginia since 1974. In 1992, the National Highway Traffic Safety Administration (NHTSA) published the final guidelines for conducting surveys of belt and helmet use in the states. As of the 1992 survey, Virginia adopted the NHTSA protocol for its statewide survey. The results showed that Virginia's summer 2006 safety belt use rate was 78.7 percent and its motorcycle helmet use rate was 99.1 percent. In the 14 previous surveys, virtually all of the motorcycle drivers and passengers observed were using a helmet. For passenger car drivers and right front passengers observed from 1992 through 2005, use rates varied from a low of 67.1 percent in 1997 to a high of 80.4 percent in the summer of 2005. The summer 2006 use rate was 1.7 percent lower than the rate for summer 2005. It should be noted, however, that any differences between annual use rates might be attributable to differences in travel patterns or other extraneous variables, such as increases in gas prices and the resulting reduction in pleasure trips, rather than solely to changes in driver and occupant behavior.

Effective determination of long-term prestress losses is important in the design of prestressed concrete bridges. Over-predicting prestress losses results in an overly conservative design for service load stresses, and under-predicting prestress losses, can result in cracking at service loads. Creep and shrinkage produce the most significant time-dependent effect on prestress losses, and research has shown that high performance and high strength concretes (HPC and HSC) exhibit less creep and shrinkage than conventional concrete. For this reason, the majority of traditional creep and shrinkage models and methods for estimating prestress losses, over-predict the prestress losses of HPC and HSC girders. Nine HPC girders, with design compressive strengths ranging from 8,000 psi to 10,000 psi, and three 8,000 psi lightweight HPC (HPLWC) girders were instrumented to determine the changes in strain and prestress losses. Several creep and shrinkage models were used to model the instrumented girders. For the HPLWC, each model over-predicted the long-term strains, and the Shams and Kahn model was the best predictor of the measured strains. For the normal weight HPC, the models under-estimated the measured strains at early ages and over-estimated the measured strains at later ages, and the B3 model was the best-predictor of the measured strains. The PCI-BDM model was the most consistent model across all of the instrumented girders. Several methods for estimating prestress losses were also investigated. The methods correlated to high strength concrete, the PCI-BDM and NCHRP 496 methods, predicted the total losses more accurately than the methods provided in the AASHTO Specifications. The newer methods over-predicted the total losses of the HPLWC girders by no more than 8 ksi, and although they under-predicted the total losses of the normal weight HPC girders, they did so by less than 5 ksi.

The rapid increase in animal-vehicle collisions on U.S. roadways is a growing concern in terms of human safety, property damage and injury costs, and viability of wildlife populations. Wildlife crossing structures are gaining national recognition by transportation agencies as effective measures to reduce animal-vehicle collisions and connect wildlife habitats across transportation corridors. In Virginia, white-tailed deer and black bear pose the highest risk. This 1-year study was conducted to monitor various underpass structures in Virginia to determine the structural and location attributes that make a crossing successful in terms of use by large mammals. The underpasses, most of which were not specifically designed as wildlife crossings, consist of box culverts and bridges of varying sizes. Remote cameras installed at seven underpass sites in Virginia have recorded more than 2,700 wildlife photographs and documented 1,107 white-tailed deer crossings in the most heavily used structures. Underpasses with a minimum height of 12 ft were successful at facilitating deer passage. Such structures were also heavily used by a variety of wildlife species, including coyote, red fox, raccoon, groundhog, and opossum. Structures with drainages that mimic natural waterways can encourage use by a diversity of terrestrial, semi-aquatic, and aquatic species. This report provides guidance in choosing cost-effective underpass design and location features that are necessary to consider to increase motorist safety and habitat connectivity. The findings also demonstrate that if only a minimal number of deer-vehicle collisions is prevented by an effective underpass, the savings in property damage alone can outweigh the construction costs of the structure

SPR 0577-030-940, The conventional methods of determining origin-destination (O-D) trip tables involve elaborate surveys, e.g., home interviews, that require considerable time, staff, and funds. To overcome this drawback, a number of theoretical models that synthesize O-D trip tables from link volume data have been developed. The focus of the research reported here was on two of these models The Highway Emulator (THE) and the Linear Programming (LP) model. These models use target/seed tables for guiding the development of output trip tables. In earlier research conducted by the Virginia Tech Center for Transportation Research for the Virginia Transportation Research Council, it was determined that the performance of these models could potentially be enhanced by using a superior target/seed table. The research in this report uses readily available socioeconomic data and link volume information to develop a methodology for obtaining an enhanced target/seed table through application of the trip generation and trip distribution steps of the four-step planning process. The enhanced table was then used as the target/seed to THE and LP models, and their performance evaluated. In addition to measuring the closeness of the output tables to surveyed tables and their capability to replicate observed volumes, their improvements over the case when a structural table is used as target was also studied. Tests showed that the use of the enhanced target/seed table significantly improved the performance of the LP model. However, mixed trends were obtained for THE.

Citizens have higher expectations for meaningful involvement in transportation decision making than ever before. Interest in an assessment of the Virginia Department of Transportation's (VDOT's) public involvement practices has originated from several sources. First, VDOT's top leadership is interested in a "tool kit," or an inventory, of current "best practices" in public involvement. Second, the Joint Legislative Audit and Review Commission's 1998 report on the highway location process in Virginia made a number of observations and suggestions about VDOT's public involvement practices. Most recently, the passage of Senate Bill 1198 (SB 1198) called attention to the open forum format VDOT uses most often for its location and design public hearings. To address these information needs, the Virginia Transportation Research Council (VTRC) developed a plan for a two-phase study of VDOT's public involvement practices. Phase I, summarized in this report, focused primarily on hearing formats and related issues. Phase II will take a much broader, more comprehensive look at all of VDOT's public involvement practices, beginning with the earliest planning stages. The results of the Phase II analysis will be summarized in one or more future reports. A 10-member project task group, with broad representation from VDOT divisions and districts and the Federal Highway Administration, will guide the VTRC's efforts during the study. The Phase I study of hearing formats and related issues reported here included a comprehensive review of the literature, a written survey for public involvement professionals in the 50 states, and a written survey for citizens attending three VDOT public hearings in 1999 (the Meadowcreek Parkway design hearing, the Capital Beltway citizen information workshops, and the Indian River Road location hearings). Two of the three projects (Meadowcreek and Capital Beltway) are controversial. Results of a previous citizen "exit survey" conducted at VDOT public heari

This report describes research to determine how the Northern Virginia Traffic Management System (TMS) operations may be improved by making modifications to the existing system. This study was completed during the period of June through September, 1993. The TMS has the potential to both improve incident response as well as provide commuters with timely traffic information. The Virginia Department of Transportation (VDOT) has made a significant investment in the TMS in terms of manpower and equipment. However, most of the TMS equipment has been in operation for nearly a decade, and many of the components have reliability problems. This results in several procedures being performed manually even though they have been designed to be performed automatically thereby placing a heavy load on TMS operators and hampering TMS effectiveness. A five person team examined both system factors, such as computers and software, and human factors, such as how the TMS operators used the resources available to them. The team made recommendations for how TMS operations might be improved through software and procedural modifications. The most essential suggestions involve maintaining a high percentage of functional loop detectors and improving the flow of information into the TMS. Improvements that would enhance TMS operations include customized software subroutines, installation of a State Police Officer at the TMS, and alterations to the variable message signs. These recommendations are detailed in the report. Although this report focuses on the Northern Virginia TMS, the authors believe that the analysis shown herein is applicable to other traffic operations centers throughout the U.S.